Ad Hoc网络的入侵检测技术研究

Ad Hoc网络是一种没有固定基础设施、网络拓扑不断变化的新型网络,固有的脆弱性使它容易受到攻击,给Ad Hoc的入侵检测带来更多挑战.文中介绍了入侵检测技术及其分类,并根据Ad Hoc网络自身的特性,总结了已有的适于Ad Hoc网络的新型的入侵检测技术及其特性.最后,提出一种基于簇的分布式入侵检测技术,对其关键技术和工作机制进行分析和阐述.     

Ad Hoc网络的关键技术分析

Ad Hoc网络是一种特殊的移动计算机网络,必须针对其网络特性采用特殊的技术和设计有效的协议。文章全面分析了Ad Hoc网络涉及的关键技术,包括MAC协议、路由协议、体系结构、分簇算法、服务质量保障机制、传输层协议、网络安全、网络管理和节能机制,旨在从总体上把握Ad Hoc网络技术及其面临的挑战。     

基于中国剩余定理的移动Ad Hoc组密钥管理

针对Ad Hoc网络自组织和分簇的特点,基于Iolus密钥管理方案的分组思想,提出一种基于中国剩余定理的适合于Ad Hoc网络的组密钥管理方式,可减少密钥更新的通信量和控制节点的存储量,降低单点失效。     

一种用于Ad Hoc网络的分簇算法

Ad Hoc网络是动态变化的拓扑结构，具有无中心和自组织的特点，如何对它进行有效地管理至今没有得到很好的解决。提出了一种基于权值的分簇算法，有效解决了这个问题，从而提高了网络管理的灵活性和可扩展性，使之更适合于管理大规模、多种环境的Ad Hoc无线网络。     

分布式无线Ad Hoc传感器网络中的合成式波束形成

分布式无线Ad Hoc传感器网络中的合作式波束形成的性能分析是建立在随机阵理论和移动通信波束形成的基础上的。在分布式Ad Hoc传感器网络中,每个传感器节点有一个全向天线,且在簇中的节点传输同一信号,使信号在远区场的目标方向上叠加。波束的方向的随机性是由无线Ad Hoc网络结构决定的。介绍了随机阵理论和移动通信波束形成,接着介绍了系统模型,分析了波束的方向特性,着重讨论了平均方向性增益,推导出平均方向性增益的近似公式。     

移动Ad Hoc网络的安全体系结构研究

移动Ad Hoc网络是一种特殊的自组织无中心多跳的无线网络，网内节点所具有的移动和分布特性使得安全成为网络设计的重点。本文首先对移动Ad Hoc网络的特点进行了介绍，然后结合移动Ad Hoc网络的特点分析了移动Ad Hoc网络面临的安全威胁，最后从系统体系结构的角度对移动Ad Hoc网络的安全问题进行了详细讨论。     

基于移动代理的无线Ad Hoc网络IDS研究

介绍了无线Ad Hoc网络的特点和面临的安全问题，分析了移动代理在Ad Hoc网络入侵检测系统中的适用性，给出了一种基于移动代理的无线Ad Hoc网络入侵检测系统模型。     

Ad Hoc 技术在未来无线通信中的角色

在未来的移动接入网中，Ad Hoc可以独立组网也可以与其他网络融合组网，大规模的独立Ad Hoc网由于其面临安全、成本、传输性能等问题，不具有商业价值。小规模的Ad Hoc网可以作为接入网并通过网关与因特网和蜂窝网络融合，能够充分利用 Ad Hoc网简单灵活等优势。[编者按]     

UWB技术在移动Ad Hoc网络中的应用研究

目前移动Ad Hoc网络的研究越来越受到人们的关注。随着超宽带(uwB)技术的发展，将其应用到移动Ad Hoc网络也成为现实。文中首先概述了移动Ad Hoc网络及其两种应用形态，然后介绍了UWB技术的背景知识。着重提出了UWB技术在移动Ad Hoc网络中应用的可行性，阐述了该应用将会遇到的问题，并从路由协议、网络QoS保证、多址接入、网络资源管理、拓扑结构设计及功率控制等关键技术探讨UWB技术对移动Ad Hoc网络的影响，最后展望了基于UWB技术的移动Ad Hoc网络的应用前景。     

基于IPSec的Ad Hoc网络安全系统的研究

分析了Ad Hoc无线多跳网络的安全问题和IPSec技术，提出了一种基于IPSec的、分布式的Ad Hoc网络的安全解决方案，建立了一个3跳无线WLAN（Wireless Local Area Network）Ad Hoc网络，并在网络上部署了作者提出的网络层安全方案，同时对网络的安全性和传输性能进行了相应的测试和评估。测试结果表明，提出的分布式IPSec安全方案在网络层上有效的加强了Ad Hoc网络的安全性能，对Ad Hoc网络本身的性能仅有轻微的影响。     

面向高动态移动自组织网络的生物启发分簇算法

分簇可以有效地提高大规模移动自组织网络的性能.但高动态的移动自组织网络具有节点移动性强、网络拓扑变化快的特点,应用传统的分簇算法会造成网络性能迅速下降,频繁的簇拓扑更新造成了簇结构的不稳定和控制开销的增加.为了解决传统分簇算法无法适应高动态的大规模移动自组织网络的问题,提出了一种基于生物启发的移动感知分簇算法,该算法对多头绒泡菌的觅食模型进行了改进,使其适用于移动自组织网络领域.由于该算法与节点的移动特性进行了结合,所以该算法可以有效地在高动态移动自组织网络中进行簇的建立与维护.实验结果表明,相较于其他传统分簇算法,本文算法提高了平均链路连接保持时间和平均簇首保持时间,使得簇结构更加稳定,提高了对高动态、大规模移动自组织网络的适应能力.     

Probabilistic analysis of routes on mobile ad hoc networks

The ad hoc network is comprised of mobile nodes without wires or any infrastructures. All data are transmitted from source node to destination node through wireless channels. The ad hoc network is self-organized by ad hoc network routing protocols. Due to the mobility of nodes, the route which is constructed from many proposed ad hoc network routing protocols and comprised of several direct node-to-node links exists only for a certain period. That also means the route is subject to frequent breakages. In this letter, the probabilistic behavior of a constructed route is investigated through simulation and curve fitting. The simulation results show that the probability density function of a route is exponential distribution. The simulation also shows how the time proportion is distributed among different route lengths under a certain scenario. The route is a basic factor in the ad hoc network which operates without any central controller. The characteristics of the route have much influence on the performance of the ad hoc network. Thus the probabilistic analysis provides important implications when we are designing ad hoc network routing protocols and deploying ad hoc networks.     

Multihop sensor network design for wide-band communications

This paper presents a master/slave cellular-based mobile ad hoc network architecture for multihop multimedia communications. The proposed network is based on a new paradigm for solving the problem of cluster-based ad hoc routing when utilizing existing wireless local area network (WLAN) technologies. The network architecture is a mixture of two different types of networks: infrastructure (master-and-slave) and ad hoc. In this architecture, the participating slave nodes (SNs) in each cluster communicate with each other via their respective master nodes (MNs) in an infrastructure network. In contrast to traditional cellular networks where the base stations are fixed (e.g., interconnected via a wired backbone), in this network the MNs (e.g., base stations) are mobile; thus, interconnection is accomplished dynamically and in an ad hoc manner. For network implementation, the IEEE 802.11 WLAN has been deployed. Since there is no stationary node in this network, all the nodes in a cluster may have to move together as a group. However, in order to allow a mobile node to move to another cluster, which requires changing its point of attachment, a handoff process utilizing Mobile IP version 6 (IPv6) has been considered. For ad hoc routing between the master nodes (i.e., MNs), the Ad hoc On-demand Distance Vector (AODV) Routing protocol has been deployed. In assessing the network performance, field test trials have been carried out to measure the proposed network performance. These measurements include packet loss, delays under various test conditions such as a change of ad hoc route, handoffs, etc.     

Channel access-based self-organized clustering in ad hoc networks

An ad hoc network is a self-organized and distributed entity consisting of a number of mobile stations (MS) without the coordination of any centralized access point. Clustering is one of the fundamental problems in ad hoc networks. In this context, we describe a distributed clustering algorithm for multihop ad hoc networks. We first propose a randomized control channel broadcast access method to maximize the worst-case control channel efficiency, based on which a distributed clustering algorithm is proposed. Both theoretical analysis and simulations indicate that the proposed clustering algorithm takes much less time and overhead to cluster a given network with more stable cluster structure, while incurring very small maintenance overhead in a dynamic network resulting from the mobility of the MS.     

Information modeling and handling for context-aware multimedia services

This article presents research challenges in wireless ad hoc networks supporting context-aware multimedia services from the point of view of different context-modeling approaches and a system architecture for context handling and delivery. Modeling techniques for context information are classified into six different categories and benchmarked according to their support with regard to 12 service requirements described in this work. One of these modeling techniques is used in the framework of a distributed context handling and delivery system that is also part of this article's contribution and a representative wireless ad hoc application scenario is presented. This end user scenario and many others are possible thanks to the flexibility and adaptability of the above mentioned context handling and delivery system     

有限区域同时同频全双工跳频自组网性能研究

该文针对有限区域的同时同频全双工(CCFD)跳频自组网络,通信节点位置不等价,受非对称互干扰和自干扰影响的场景,开展有限区域全双工跳频自组网的通信性能分析。以网络频带利用率为性能指标,推导出节点位置分布条件下的网络频带利用率闭合表达式,并提出一种降低网络互干扰的节点位置优化分布方法。理论和仿真结果表明,有限区域全双工跳频自组网的性能与频点个数、通信距离、节点个数强相关,且全双工自组网络的性能与半双工网络相比,其占优区域受节点个数约束。     

一种低开销自适应SD­­­－UANET流表下发机制

软件定义无人机自组网场景下,相较于软件定义有线网络,其网内节点数量更多导致各节点流表数量爆发式增长。针对原OpenFlow v1.5协议中主动下发流表的机制与flow_mod消息结构对于无线环境与多跳流表下发的不兼容,导致无人机自组网场景下流表下发开销过大以及收包率降低。对于无人机自组网场景下OpenFlow v1.5协议中的问题,通过组播切包组包去尾策略与流表源、目的地址自适应压缩策略,减少了头部开销,提升了无线资源利用率,并减少了冗余的流表项部分,在保证功能不缩减的情况下较显著地减少了开销。OPENET 14.5仿真验证显示,此机制大幅减少了网络控制开销,提高了网络吞吐量,降低了端到端时延与丢包率。     

Suitability of ad hoc routing in WNR: Performance evaluation and case studies

A major issue in the application of ad hoc networking to Wireless Networked Robotics is the choice of the routing protocol that performs better in a given scenario. However, far too little attention has been paid to routing issues involving enhanced robotic nodes. In view of the lack of a significant and comprehensive analysis, this research work completes an in-depth performance comparison of mostly well-known ad hoc routing protocols under a wide variety of conditions and applies the obtained results to a case study with three examples of real-world Wireless Networked Robotics scenarios.     

Ad hoc networking with directional antennas: a complete system solution

Directional antennas offer tremendous potential for improving the performance of ad hoc networks. Harnessing this potential, however, requires new mechanisms at the medium access and network layers for intelligently and adaptively exploiting the antenna system. While recent years have seen a surge of research into such mechanisms, the problem of developing a complete ad hoc networking system, including the unique challenge of real-life prototype development and experimentation has not been addressed. In this paper, we present utilizing directional antennas for ad hoc networking (UDAAN). UDAAN is an interacting suite of modular network- and medium access control (MAC)-layer mechanisms for adaptive control of steered or switched antenna systems in an ad hoc network. UDAAN consists of several new mechanisms-a directional power-controlled MAC, neighbor discovery with beamforming, link characterization for directional antennas, proactive routing and forwarding-all working cohesively to provide the first complete systems solution. We also describe the development of a real-life ad hoc network testbed using UDAAN with switched directional antennas, and we discuss the lessons learned during field trials. High fidelity simulation results, using the same networking code as in the prototype, are also presented both for a specific scenario and using random mobility models. For the range of parameters studied, our results show that UDAAN can produce a very significant improvement in throughput over omnidirectional communications.     

Design and demonstration of policy-based management in a multi-hop ad hoc network

In this paper, we propose a policy-based framework for the management of wireless ad hoc networks and briefly describe a characteristics-based taxonomy that provides a platform to analyze and compare different architectural choices. We develop a solution suite that helps achieve our goal of a self-organizing, robust and efficient management system. One of the main contributions of this work is the prototype implementation and testing of the mechanisms and protocols comprising our framework in a multi-hop ad hoc network environment. Experiments are conducted using both an emulated ad hoc network testbed and a true wireless testbed. Degradation in management system performance is observed as the number of hops between a policy server and client increases. Our proposed k-hop clustering algorithm alleviates this problem by limiting the number of hops between a server and client. We demonstrate the operation of our prototype implementation, illustrating QoS management in a multi-domain ad hoc network environment using the proposed cluster management, redirection, and policy negotiation mechanisms.